1. Field of the Invention
The present invention relates to efficient control of an elevator system wherein a plurality of cars are provided at top and bottom in a single shaft and the plural cars are connected to each other, or an elevator system wherein a plurality of cars are provided at top and bottom in a single shaft and the plural cars are able to freely move.
2. Description of Related Art
In recent years, technologies have been reported regarding a double-decker elevator (hereinafter referred to as xe2x80x9cDD elevatorxe2x80x9d) wherein a plurality of cars are provided at top and bottom in a single shaft and relative positions of the plural cars are fixed, or a multi-cage elevator (hereinafter referred to as xe2x80x9cMCxe2x80x9d elevator) wherein a plurality of cars are provided at top and bottom in a single shaft and the plural cars can freely move. When a plurality of cars or elevator systems are provided, group control is usually carried out. There has also been a technological report on group control for the DD elevators or the MC elevators.
Regarding a DD elevator, in particular, there is a technological report given below.
(a) It is a basic rule in a DD elevator to make a lower car respond to a call for raising a car and to make an upper car to respond a call for lowering a car. If a call is generated on a floor adjacent to a floor where an already assigned call exists, then assignment is performed so as to enable a response to be given to these calls at the same time. (Japanese Examined Patent Publication No. 51-12898)
(b) A destination registering apparatus is installed at a hall, and calls for cars corresponding to destination floors are separately assigned to the upper and lower cars. The destination floors of the cars are displayed when the cars arrive. (Japanese Unexamined Patent Publication No. 4-345476)
The prior art has been posing the following problems.
An attempt in (a) above is to simultaneously respond to the calls from the adjacent floors. According to this method, however, there have been some cases wherein simultaneous responses are impossible, depending on a sequence in which calls occur. For instance, if the lower car is assigned first to a call made at a hall of a fifth floor to a request for going up, and a call is secondly made at a hall of a sixth floor to request for going up, then the upper car is assigned to the second call, thus making it possible to simultaneously respond to both calls. Conversely, however, if the call at the fifth floor takes place after the call at the sixth floor, then the lower car is assigned first to the call at the sixth floor, making it impossible to respond to the two calls at the same time.
In (b) above, the destination floors are displayed when the cars arrive at the halls in the DD elevator thereby to prevent passengers from becoming confused. However, no description is given to how to improve operation efficiency.
The present invention has been made with a view toward solving the problems described above, and it is an object of the invention to provide an elevator controller capable of carrying out more efficient group control on a DD elevator or an MC elevator.
To this end, according to one aspect of the present invention, there is provided an elevator system in which a plurality of cars are provided at top and bottom in the same shaft, comprising: a call registerer for entering a hall call; a tentative assignment finalizing unit for tentatively assigning a first car in response to a first call entered by the call registerer; and a reassigning unit for changing an assignment for the first call to a second car that is different from the first car after tentatively assigning the first car, depending upon a traffic situation of the elevator system.
In a preferred form, the reassigning unit changes the assignment for the first call if a second call that is different from the first call occurs after the first car has been tentatively assigned.
In another preferred form, the reassigning unit determines whether a predetermined time before the first car arrives at the floor where the first call occurred has been reached or not, and if the predetermined time has not been reached, then the assignment for the first call is changed.
In another preferred form, the reassigning unit changes the assignment in response to the first call to the second car in the shaft wherein the first car is in service.
In yet another preferred form, the call registerer registers a call by entering a destination floor, and the reassigning unit changes an assignment performed in response to the first call according to a destination floor entered at the first call and a destination floor entered at the second call.
In a further preferred form, the call registerer registers a call by entering a destination floor, and further comprising a display for displaying a destination floor of the second car according to a result of reassignment performed by the reassigning unit.
In another preferred form, the elevator system further comprises an operation controller that issues a stop command for stopping the second car at a destination floor specified by the first call and instructs the display to display the destination floor of the second car after a reassignment is performed by the reassigning unit.
According to another aspect of the present invention, there is provided an elevator system in which a plurality of shafts are provided and a plurality of cars are provided at top and bottom in each shaft, comprising: a call registerer for entering a hall call; a tentative assignment finalizing unit for deciding on a shaft to be assigned in response to a first call entered by the call registerer and for tentatively assigning a first car in the shaft; and a reassigning unit for changing an assignment for the first call to a second car in the shaft decided on by the tentative assigning unit after tentatively assigning the first car, depending upon a traffic situation of the elevator system.
According to yet another aspect of the present invention, there is provided a car assignment control method for an elevator system having a plurality of cars provided at top and bottom in the same shaft, comprising the steps of: entering a first call; a tentatively assigning a first car to the first call; and changing the assignment for the first call to a second car that is different from the first car, depending on a traffic situation of the elevator system.